MeCOCH=C(Me)O anion
- Formula: C5H7O2-
- Molecular weight: 99.1084
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Reaction thermochemistry data
Go To: Top, Gas phase ion energetics data, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data compiled by: John E. Bartmess
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Individual Reactions
By formula: C5H7O2- + H+ = C5H8O2
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 343.8 ± 2.1 | kcal/mol | G+TS | Taft and Bordwell, 1988 | gas phase; at 330K: neutral enol/keto ratio should be 8:1 ( Strohmeier and Höhne, 1952) |
ΔrH° | 343.7 ± 2.3 | kcal/mol | G+TS | Cumming and Kebarle, 1978 | gas phase; At 500K: neutral enol/keto ratio is 1.7:1, Folkendt, Weiss-Lopez, et al., 1989. ΔH=-4.7 kcal/mol, enol favored. Carbonyls anti in anion, via calc: Irikura, 1999 |
Quantity | Value | Units | Method | Reference | Comment |
ΔrG° | 336.7 ± 2.0 | kcal/mol | IMRE | Taft and Bordwell, 1988 | gas phase; at 330K: neutral enol/keto ratio should be 8:1 ( Strohmeier and Höhne, 1952) |
ΔrG° | 336.6 ± 2.0 | kcal/mol | IMRE | Cumming and Kebarle, 1978 | gas phase; At 500K: neutral enol/keto ratio is 1.7:1, Folkendt, Weiss-Lopez, et al., 1989. ΔH=-4.7 kcal/mol, enol favored. Carbonyls anti in anion, via calc: Irikura, 1999 |
Gas phase ion energetics data
Go To: Top, Reaction thermochemistry data, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data compiled by: John E. Bartmess
Electron affinity of neutral species
EAneutral (eV) | Method | Reference | Comment |
---|---|---|---|
2.64 ± 0.19 | D-EA | Cumming and Kebarle, 1978 | At 500K: neutral enol/keto ratio is 1.7:1, Folkendt, Weiss-Lopez, et al., 1989. ΔH=-4.7 kcal/mol, enol favored. Carbonyls anti in anion, via calc: Irikura, 1999 |
2.52 ± 0.13 | IMRB | Sharpe and Richardson, 1991 | MP2/6-31+G*: EA 2.8 eV, in sickle geometry, 99IRI |
Protonation reactions
By formula: C5H7O2- + H+ = C5H8O2
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 343.8 ± 2.1 | kcal/mol | G+TS | Taft and Bordwell, 1988 | gas phase; at 330K: neutral enol/keto ratio should be 8:1 ( Strohmeier and Höhne, 1952) |
ΔrH° | 343.7 ± 2.3 | kcal/mol | G+TS | Cumming and Kebarle, 1978 | gas phase; At 500K: neutral enol/keto ratio is 1.7:1, Folkendt, Weiss-Lopez, et al., 1989. ΔH=-4.7 kcal/mol, enol favored. Carbonyls anti in anion, via calc: Irikura, 1999 |
Quantity | Value | Units | Method | Reference | Comment |
ΔrG° | 336.7 ± 2.0 | kcal/mol | IMRE | Taft and Bordwell, 1988 | gas phase; at 330K: neutral enol/keto ratio should be 8:1 ( Strohmeier and Höhne, 1952) |
ΔrG° | 336.6 ± 2.0 | kcal/mol | IMRE | Cumming and Kebarle, 1978 | gas phase; At 500K: neutral enol/keto ratio is 1.7:1, Folkendt, Weiss-Lopez, et al., 1989. ΔH=-4.7 kcal/mol, enol favored. Carbonyls anti in anion, via calc: Irikura, 1999 |
References
Go To: Top, Reaction thermochemistry data, Gas phase ion energetics data, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Taft and Bordwell, 1988
Taft, R.W.; Bordwell, F.G.,
Structural and Solvent Effects Evaluated from Acidities Measured in Dimethyl Sulfoxide and in the Gas Phase,
Acc. Chem. Res., 1988, 21, 12, 463, https://doi.org/10.1021/ar00156a005
. [all data]
Strohmeier and Höhne, 1952
Strohmeier, W.; Höhne, I.,
Keto-Enol-Umwandlung des Acetylacteons in Gaszustand,
Z. Naturfor., 1952, 7B, 184. [all data]
Cumming and Kebarle, 1978
Cumming, J.B.; Kebarle, P.,
Summary of gas phase measurements involving acids AH. Entropy changes in proton transfer reactions involving negative ions. Bond dissociation energies D(A-H) and electron affinities EA(A),
Can. J. Chem., 1978, 56, 1. [all data]
Folkendt, Weiss-Lopez, et al., 1989
Folkendt, M.M.; Weiss-Lopez, B.E.; Chauvel, J.P., Jr.; True, N.S.,
Gas-Phase 1H NMR Studies of Keto-Enol Tautomerization of Acetylacetone, Methyl Acetoacetate, and Ethyl Acetoacetate,
J. Phys. Chem., 1989, 89, 15, 3347, https://doi.org/10.1021/j100261a038
. [all data]
Irikura, 1999
Irikura, K.K.,
Acetylacetonate (acac) anion in the gas phase: predicted structures, vibrational spectra, and photodetachment energies,
Int. J. Mass Spectrom., 1999, 187, 577-587, https://doi.org/10.1016/S1387-3806(98)14192-1
. [all data]
Sharpe and Richardson, 1991
Sharpe, P.; Richardson, D.E.,
Metal-Ligand Bond Energies and Solvation Energies for Gas-Phase Transition Metal Tris(acetylacetonate) Complexes and their Negative Ions,
J. Am. Chem. Soc., 1991, 113, 22, 8339, https://doi.org/10.1021/ja00022a021
. [all data]
Notes
Go To: Top, Reaction thermochemistry data, Gas phase ion energetics data, References
- Symbols used in this document:
EAneutral Electron affinity of neutral species ΔrG° Free energy of reaction at standard conditions ΔrH° Enthalpy of reaction at standard conditions - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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